This invention relates to machine tools of the screw thread cutting type.
More specifically, the invention relates to an automatic thread cutting apparatus which allows the screw pitch to be set and adjusted while the screw thread is being cut thereby obtaining a high production rate.
A number of known apparatuses of this type use a press movement, i.e., a descending and reascending movement, to control the feed and the return stroke of the screw tap. This type of apparatus does not allow the screw pitch to be adjusted, the feed and recoil disturbances of the screw taps being compensated by a damping device including a spring located between the control of the motion of rotation and the feed control of the screw tap. This arrangement is not mechanical thus requiring experienced personnel specialized on this particular type of machine tool, the cutting speed being partially compensated by the waste of time and the numerous breakdowns of the screw taps during operation this further decreasing general efficiency.